1. Field of the Invention
The present invention relates to an improvement of a color ink ribbon and a printer using this ribbon.
2. Description of the Related Art
In a color ink ribbon used for, e.g., a color bar code printer, three primary colors, i.e., yellow (Y), magenta (M), and cyan (C) are sequentially aligned in the ribbon feeding direction. In addition, color recognition marks (bar codes) representing the types of primary color are formed immediately before portions of the three primary colors. A detector is arranged in a printer using this color ink ribbon to detect a color recognition mark of each of the three primary colors. The next color of the ink ribbon fed by a ribbon drive motor is detected in accordance with a detection output (i.e., a color recognition mark read output) from this detector. More specifically, black level detection outputs from the color recognition mark detector are counted to recognize a bar code width of each color recognition mark in accordance with the count. If the recognized bar code width is only width a, the color is discriminated as yellow (Y). If the width is a combination of width a and width 2a, the color is discriminated as magenta (M). If the width is only width 2a, the color is discriminated as cyan (C). Cuing of the ink ribbon corresponding to printing data is performed, and then a color image is printed on paper by a thermal head or the like.
Most of the color ink ribbon is wound around a ribbon supply core in an initial condition, and the color ink ribbon is sequentially supplied upon constant-speed rotation of the ribbon drive motor and is taken up by a ribbon take-up core. In an end condition, the most of the ribbon has already been taken up by the ribbon take-up core. Therefore, the ink ribbon feeding speed in the initial condition is different from that in the end condition. In particular, when the overall length of the ribbon is large or a core diameter is small, a speed difference is large.
Since a color to be fed next is determined by recognizing the width of a bar code formed on the ink ribbon, as described above, a large speed difference tends to cause color discrimination errors because the width of each bar code is erroneously detected. For this reason, an ink ribbon having a small overall length or a large core is conventionally used to overcome the above problem.
As described above, in the conventional color ink ribbon, since each bar code represents only the next color, color discrimination is erroneously performed by a change in ribbon feeding speed. For this reason, only a wasteful color ink ribbon having a small overall length or a large core is used in a color printer to always perform accurate color discrimination.